Light-metal alloy



Patented June 1929.

UNITED STATES JOHN A. GANN, OF MIDLAND, MICHIGAN, ASSIGNOR TO THE DOWCHEMICAL COM- PANY, 0F MIDLAND, MICHIGAN, A CORPORATION OF MICHIGAN.

LIGHT-METAL ALLOY.

No lirawin Application filed October 18, 1922,

The present improved alloy is one in which magnesium is the predominantelement, such mnetal being preferably present in excess of 80 per cent,as prescribed in U. S. Patent No,

" 905,485 to listor et al., dated Jul. 20, W10. The other added metalsincliulb copper, aluminum and cadmium, the copper being added inflll'lOlllltS greater than those of aluminum and cadmium.

As noted in Reinglass treatise on Alloys (see page 175), the Frenchpatent to Walter Ri'ihel, No. 407,814, dated October 12, 1909, suchpatent corresponding in part to his U.

S. Patent No. 982,022, dated January 17, 1.911., suggests-that the zincin this patentees magnesium-zinc formula may be partly replaced bycopper or entirely by aluminum-and copper. ()ue illustrative formula ofthe latter ternary alloy is as follows, viz, magnesium 90 per cent,copper 9 per cent and aluminum 1 per cent.

I have found that magnesium-copper alloys are not very strong andfurthermore are not particularly good for casting purposes and thatthe'addition of a little aluminum, in accordance with the Riibel formulajust cited, greatly improves both the strength and the casting)roperties of such magnesium-copper alloy. n the other hand, theaddition of a little cadmium to such magnesium-copper alloy does notappreciably improve the alloy; in fact, it often gives a very inferiorcastin If, however, instead of dealing with sudh magnesium-copper alloy,we take a magnesiuiii-copper-aluminum alloyofapproximatelythecomposition described by Riibel and add a small amount of cadmiumJ havefound that an alloy is produced that is considerably better-than theoriginal ternary alloy. In other words, the resulting quarternarymagnesium-copper-aluminum-cadmium alloy presents superior qualities bothfrom the standpoint of strength and toughness and that of casting andgeneral workability.

The composition of my improved alloy will now be full described andparticularly pointed out 1n the claims, it being understood that thefollowing description sets forth but several of the various ways inwhich the principle of the invention may be carried out.

The ranges .of composition that have been found satisfactory for use inmy improved quarternary alloy are as follows, viz, cop- I per lie 12 percent (4 to 8 per cent being Serial No. 595,277. Renewed September 1,1926.

preferred), aluminum 1 to 4 per cent (1 to 2 per cent being preferred),cadmium 1' to 4 per cent (2 to 3 per cent being preferred), andmagnesium constituting the balance.

A specific formula that has proven very satisfactory, both in test andactual use, is as follows, viz, magnesium 92 per cent, c0 per 4: percent, aluminum 2 per cent, cad mium 2 per cent. The physical propertiesof this particular alloy have been determined to be as follows, viz,tensile strength 20,000 to 22,000 lbs. per square inch; thermalconductivity 0.30; single-blow impact-toughness and Brinell hardness 45.As compared with other commercial light-metal alloys wherein magnesiumis the predominant ingredient, my new alloy would appear to haveapproximately the same tensile strength combined with a somewhat greatertoughness, as indicated by the single-blow impact number, a somewhatlower Brinell hardness, and a much higher thermal conductivity.

Accordingly, it would appear that the addition of cadmium to a ternarymagnesiumcopper-aluminum alloy of the type in hand, wherein the amountof copper is" in excess of that of aluminum, materially increases thestrength and toughness of the resulting product and so presents aneffect that would be wholly unsuspected from the elfect of addingcadmium to a binar magnesium-copper alloy. It Will be understood thatthe physical properties of my improved alloy may be modified-by theadditions of small amounts of other metals such as zinc and tin. Wherezinc is thus employed, the amount thereof will desirably be kept withinthe range where such zinc will dissolve in the magnesium, i. e., enterinto solid solution. With this in mind, the amount of zinc recommendedis from 0.30 per cent to 0.65 per cent, only, while the amount of tin,where this metal is added, SllOLild not greatly exceed 1 per cent of thetota ()ther modes of applying the principle of my invention may beemployed instead of the one explained, change being made as regards thematerials employed, provided the ingredients stated by any of thefollowing claims or the equivalent of such stated ingredients beemployed.

'I therefore particularly point out and dismium, wherein the magnesiumlargely predominates and the amount of the copper ranges fromapproximately 3 to 12 per cent, the amount of copper exceeding that ofaluminum and the latter as well as the cadmium being present insubstantial amounts.

- 2. As a new product, an alloy consistin of magnesium, copper, aluminumand mium, wherein the magnesium is in excess of 80 per cent and theamount of the copper ranges from a proximately 3 to 12 per cent, theamount 0 copper being approximately twice that of aluminum and thelatter as well as the cadmium being present in substantial of magnesium,copper, aluminum and cadcadmium from 1 to 4 per cent of the total.

4:. As a new product, an alloy containing magnesium, copper, aluminumand cadmium,

wherein the magnesium largely predominates, 25 the copper being from 4to 8 per cent, the aluminum from Ito 2 per cent, and the cadmium from 2to 3 per cent of the total.

5. As a new product, an alloy containing approximately 92 per cent of maesium, 4 per cent of copper, 2 per cent of a uminum and 2 per cent ofcadmium.

Signed by me, this 14 day of October, 1922.

JOHN A. GANN.

